:''For the band, see Helmet (band). For the post-Roman kingdom in north England, see Elmet''.
A '''helmet''' is a form of protective clothing worn on the head and usually made of metal or other hard substance, such as Kevlar, resin fiber, or plastic typically for protection of the head in combat, or in civilian life, from sports injuries, falling objects or high-speed collisions.
Helmets are common in the military, construction, mining, and some sports, including American football, baseball, ice hockey, equestrian sports, and rock climbing. Motorcycle helmets and bicycle helmets are compulsory headgear in some jurisdictions; in the United Kingdom only Sikhs are allowed to ride motorcycles without wearing motorcycle helmets. Bicycle helmet compulsion and even strong promotion has been a heated subject of debate amongst cyclists and scientists since at least the 1990's, lately focusing on alleged net protective effect at the population level.
Etymology
The English word ''helmet'' arose by Anglo-Saxon ''helm'' = "helmet" coalescing with a French diminutive of French ''heaume'', Old French ''helme'', from Frankish German ''helm''. The origin is Proto-Germanic ''*khelmaz'' from PIE ''*kelmo-'' "a cover". The diminutive ending ''-et'' was to distinguish ordinary helmets from the knights' great helm.
Helmets' original military usage and symbolism
Helmets are among the most ancient forms of combat protection, and are known to have been worn by ancient Greeks, Romans, throughout the Middle Ages, and up to the end of the 1600s by many combatants. At that time they were purely military equipment, protecting the head from cutting blows with swords, flying arrows, and low velocity musketry. They were initially constructed from leather, but soon came to be made entirely from forged steel after about 950A.D. Military use of helmets declined after 1670, and rifled firearms, after 1700, ended their use by foot soldiers. 18th century cavalry units often wore steel body cuirasses, and frequently wore metal skull protectors under their hats, called "secrets". The often ridiculed Prussian spiked helmet did nevertheless save many soldiers by diverting sideways otherwise mortal sabre blows to the head; it was retained in the age of the machine gun merely for tradition.
The Napoleonic era saw ornate cavalry helmets reintroduced for cuirassiers and dragoons in some armies; they continued in use until the first year of World War I.
With World War I and the use of heavy artillery, the steel helmet made a quick comeback for foot soldiers. In the 20th Century it offered protection for the head from shrapnel and spent or glancing bullets. The use of protective helmets by millions of fighting men in the two world wars increased awareness of "hard hat" protection. By the 1950s, hundreds of new applications
